Often you would want to carry electronic devices in flight. These items could be laptops, mobile phones, cameras, tablets, electronic cigarettes also called vapes, power-banks, smart bags, electric wheelchairs, and other such items that have lithium batteries.

These devices either have lithium ion or lithium metal batteries.
The lithium ion batteries are rechargeable and its power is measured in Watt-hour but the lithium metal batteries are non-rechargeable and its power is measured in grams of metal content.
These batteries are either carried installed in the device or as spares.
If it is installed in device, then whether it can be removed or not is also a matter of consideration.
There are specific FAA and IATA guidelines for carrying these devices or spares in the flight.

FAA and IATA guidelines

Lithium ion batteries of up to 100watt hour power rating, OR, having Lithium metal content of up to 2 grams, whether installed in device or being carried as spare batteries, can be taken in carry-on baggage.
But, in check-in baggage, only devices are allowed. Spare batteries are not allowed in check-in baggage.
No approval from airlines is required.

If Lithium ion content in batteries is more than 100Wh but less than 160Wh, then approval from the airline is needed.
Both the devices and the spares can be carried in cabin baggage.
If the power of Lithium ion batteries is more than 160Wh, then the items or spares have to be carried as cargo.

For carrying Lithium ion metal content batteries either in devices or spares with metal content more than 2 grams but less than 8 grams, then only medical devices or spares for medical devices are allowed with the approval of airline. Both of these can be carried in carry-on baggage. But, only medical devices are allowed in check-in baggage, not the spares.

Summary
All portable electronic devices having lithium batteries shall ideally be carried in cabin bag.
If at all these have to be carried in check-in baggage, it shall be switched off and shall be packed safely.
Spare Lithium batteries have to be individually protected by insulating terminals. These are only allowed on cabin baggage.
It is to be noted that power-banks are considered spare batteries and each of these shall be kept in separate plastic pouch in cabin baggage.
Electronic Cigarettes or Vapes have to be carried only in Cabin baggage but are not to be recharged on-board.